低密度奇偶校验码级联水印码的编译码方案可纠正非二进制同步错误。为了提高上述系统中水印码识别同步错误的能力,提出了扩展多个符号子集的改进水印调制方案。具体而言,该改进方案将每个传输符号携带的水印信息扩展至两位,对应地将传...低密度奇偶校验码级联水印码的编译码方案可纠正非二进制同步错误。为了提高上述系统中水印码识别同步错误的能力,提出了扩展多个符号子集的改进水印调制方案。具体而言,该改进方案将每个传输符号携带的水印信息扩展至两位,对应地将传输信号的子集扩展为四个。扩展后的系统星座图的划分更为精细,提高了借助更多水印比特码识别同步错误的能力。仿真结果表明,与传统方案相比,在加性噪声较小情况下如信噪比为10 d B,当误帧率为10^(-3)时,改进方案可以纠正的同步错误概率达13%,且适用于非线性信道。展开更多
Watermarking system based on quantization index modulation （QIM） is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronizati...Watermarking system based on quantization index modulation （QIM） is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronization attacks of QIM digital watermarking,a low density parity check （LDPC） code-aided QIM watermarking algorithm is proposed,and the performance of QIM watermarking system can be improved by incorporating LDPC code with message passing estimation/detection framework.Using the theory of iterative estimation and decoding,the watermark signal is decoded by the proposed algorithm through iterative estimation of amplitude scaling parameters and decoding of watermark.The performance of the proposed algorithm is closer to the dirty paper Shannon limit than that of repetition code aided algorithm when the algorithm is attacked by the additive white Gaussian noise.For constant amplitude scaling attacks,the proposed algorithm can obtain the accurate estimation of amplitude scaling parameters.The simulation result shows that the algorithm can obtain similar performance compared to the algorithm without desynchronization.展开更多
A multipurpose image watermarking technique based on DCT is proposed to notify and protect the copyright of digital products. In order to achieve this objective, the DCT coefficients of each image block are divided in...A multipurpose image watermarking technique based on DCT is proposed to notify and protect the copyright of digital products. In order to achieve this objective, the DCT coefficients of each image block are divided into two parts for embedding the visible and invisible watermarks. The visible watermark is embedded in each DC DCT coefficient and most of the AC DCT coefficients of every block, and the invisible watermark in the rest. Based on the characteristics of Human Visual System (HVS), the embedding strength of the visible watermark is varied in accordance with the underlying content of the host image. The invisible watermark is embedded in a quaternity of midrange frequencies. Experimental results show that the visible watermark is hard to remove and the invisible watermark is robust to common digital signal processing operations.展开更多
文摘低密度奇偶校验码级联水印码的编译码方案可纠正非二进制同步错误。为了提高上述系统中水印码识别同步错误的能力,提出了扩展多个符号子集的改进水印调制方案。具体而言,该改进方案将每个传输符号携带的水印信息扩展至两位,对应地将传输信号的子集扩展为四个。扩展后的系统星座图的划分更为精细,提高了借助更多水印比特码识别同步错误的能力。仿真结果表明,与传统方案相比,在加性噪声较小情况下如信噪比为10 d B,当误帧率为10^(-3)时,改进方案可以纠正的同步错误概率达13%,且适用于非线性信道。
基金National Natural Science Foundation of China(No.61272432)Qingdao Science and Technology Development Plan(No.12-1-4-6-(10)-jch)
文摘Watermarking system based on quantization index modulation （QIM） is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronization attacks of QIM digital watermarking,a low density parity check （LDPC） code-aided QIM watermarking algorithm is proposed,and the performance of QIM watermarking system can be improved by incorporating LDPC code with message passing estimation/detection framework.Using the theory of iterative estimation and decoding,the watermark signal is decoded by the proposed algorithm through iterative estimation of amplitude scaling parameters and decoding of watermark.The performance of the proposed algorithm is closer to the dirty paper Shannon limit than that of repetition code aided algorithm when the algorithm is attacked by the additive white Gaussian noise.For constant amplitude scaling attacks,the proposed algorithm can obtain the accurate estimation of amplitude scaling parameters.The simulation result shows that the algorithm can obtain similar performance compared to the algorithm without desynchronization.
文摘A multipurpose image watermarking technique based on DCT is proposed to notify and protect the copyright of digital products. In order to achieve this objective, the DCT coefficients of each image block are divided into two parts for embedding the visible and invisible watermarks. The visible watermark is embedded in each DC DCT coefficient and most of the AC DCT coefficients of every block, and the invisible watermark in the rest. Based on the characteristics of Human Visual System (HVS), the embedding strength of the visible watermark is varied in accordance with the underlying content of the host image. The invisible watermark is embedded in a quaternity of midrange frequencies. Experimental results show that the visible watermark is hard to remove and the invisible watermark is robust to common digital signal processing operations.
